Field of the Invention
The invention relates to a polishing pad and a polishing system and particularly relates to a polishing pad, a polishing system, and a polishing method that achieve a relatively uniform removal rate.
Description of Related Art
With the advancement of industries, planarizing processes are often used as processes for manufacturing various devices. Among the planarizing processes, chemical mechanical polishing is commonly used by the industries. Generally, the chemical mechanical polishing (CMP) process is carried out by attaching a polishing pad to a polishing platen, supplying a slurry which contains chemicals on the polishing pad, applying a pressure on the object to be polished (e.g., semiconductor wafer) to press it against the polishing pad, and then moving the object to be polished and the polishing pad relative to each other. Through the mechanical friction generated by the relative movement and the chemical reaction of the slurry, a part of the surface of the object is removed to gradually planarize the surface, thereby achieving the purpose of planarization.
FIG. 1A is a schematic top view of a conventional polishing pad. Referring to FIG. 1A, a polishing pad 10A includes a plurality of concentric grooves 14 that are formed on a surface of a polishing layer 12 of the polishing pad 10A for accommodating and transporting a slurry. However, the concentric grooves 14 are not connected with one another, so the transportation of the slurry is not good enough between different regions of the surface of the polishing layer 12. Particularly, the slurry flow distribution in the region corresponding to the center region of an object to be polished 20 may be not good enough and result in a non-uniform removal rate of the object to be polished 20.
FIG. 1B is a schematic top view of another conventional polishing pad. Referring to FIG. 1B, a surface of a polishing layer 12 of a polishing pad 10B further has grid-shaped grooves 16 thereon in addition to the multiple concentric grooves 14. The grid-shaped grooves 16 are connected in order to improve the efficiency of transportation of the slurry. For specific polishing processes, however, it may have too much slurry flow distributed in the region corresponding to the center region of the object to be polished 20. As a result, the problem of non-uniform removal rate still exists.
In view of the above, for specific polishing processes, a polishing pad having different slurry flow distribution is required in order to meet the demands of the industries.